What is the Best Energy Source for Off-highway Powertrains?

Transcription

1 Professor Colin Garner PhD, FREng Chair in Applied Thermodynamics Loughborough University 1

2 Types of machines: A) Tethered B) Semi-Tethered e.g. electric trains [1] Electrical energy normally from electricity grid C) Non-tethered Geographic flexibility On-board energy The focus of this presentation 2

3 Types of Vehicle/Machine Powertrain Systems: Primary On-Board Energy Source: Key: = Energy Flows IC Engine Fuel Tank IC Engine and IC Engine-hybrid Fuel Tank IC Engine and Regeneration System/Store e.g. Battery Battery Electric Battery Motor(s) and 3

4 Types of Vehicle/Machine Powertrain Systems: Primary On-Board Energy Source: Key: = Energy Flows IC Engine Fuel Tank IC Engine and IC Engine-hybrid Fuel Tank IC Engine and X Regeneration System/Store e.g. Battery Battery Electric Battery Motor(s) and 4

5 Types of Vehicle/Machine Powertrain Systems: Primary On-Board Energy Source: Key: = Energy Flows IC Engine Fuel Tank IC Engine and IC Engine-hybrid Fuel Tank IC Engine and Regeneration System/Store e.g. Battery Battery Electric Battery Motor(s) and 5

6 1. Global and Local Emissions 2. Energy and Power 3. Comparison - IC Engine/ICE Hybrid vs Pure Battery powertrain 4. Utility of Diesel Fuel and IC Engines 5. Energy Production 6. Conclusions 6

7 1. Global and Local Emissions Stage V emissions very low; e.g. PM <0.015 g/kw.hr PN <10 12 particles/kw.hr >23 nm kw power range NOx <0.4 g/kw.hr ~4.4% NOx and ~2.1% PM of 1999 Stage I emissions levels Machine fuel economy high; hence low CO 2 7

8 2. Energy and Power Energy: Joules, J High values allow us to do a lot of work Power: Rate of energy, Joules per second = Watts, W High values allow us to do a lot of energy transfer and work quickly The car time machine Flux Capacitor needed 1.21 GW of power, so a lightning strike was used 8

9 Energy: Joules, J High values allow us to do a lot of work Need a prime on-board energy store i.e. Fuel tank or Battery pack What is best? Fuel energy from fuel supply ICE or ICE-hybrid Fuel tank Pure Battery Electric Battery pack Electrical energy from electricity grid 9

10 Battery Capability now and future: The UK Automotive Council in 2017 set several targets for the battery Faraday Challenge to meet by year 2035, as follows: Reduce battery cell cost from 100/kWh to 38/kWh (i.e. 28/MJ to 10/MJ) Double a battery cell s energy density, from 250 Wh/kg to 500 Wh/kg (i.e. 0.9 MJ/kg to 1.8 MJ/kg) Increase a battery cell s coldest operating temperature from -20 C to -40 C, and hottest operating temperature from 60 C to 80 C Improve a battery pack s recyclability from 10-50% to 95% Source: [2] 10

11 3. Comparison IC Engine (or ICE-Hybrid) machine versus Battery-only machine Using year 2035 target battery cell values: Example: Machine with Diesel fuel tank volume = 150 litres Assume: Engine brake fuel conversion efficiency is only 33% Assume: Battery-electric system is 100% efficient Assume: Lower Heating Value of diesel fuel = 42.5 MJ/kg 150 litre fuel tank Battery Year 2035 Effective energy in store 1.77 x 10 9 J 1.77 x 10 9 J Battery Year x 10 9 J Mass of the energy store ~ 160 kg (including the fuel) 983 kg (just for the cells) 1967 kg Cost of energy store ~ 100 (tank; pipes; sensors) 17,700 (just for the cells) 49,560 11

12 3. Comparison IC Engine (or ICE-Hybrid) machine versus Battery-only machine Energy store filling or charging rate: 1.77 x 10 9 J of effective energy needs to be delivered Fuel energy from fuel supply Fuel tank 150 litres at fuelling rate of 50 litres per minute = 3 minutes = 180 secs: (1.77 x 10 9 / 180 ) J/sec (i.e. W) = 9.83 MW Electrical energy from electricity grid Battery Pack 9.83 MW of electrical charge rate is impractical (i.e. the sheer amount and the heating effect) A 120 kw battery fast-charger system would take 4 hours if linear Access to a charger? Big challenge 12

13 4. Utility of Diesel Fuel and IC Engines Utility of Using Diesel Fuel: 1. High oil reserves / production (R/P) ratio > 50 years [3] 2. Low production costs and energy for processing the fuel 3. Relatively safe and cheap to store [e.g. you can have 3,500 litres of fuel oil at your house [4] ] 4. Easy to store and handle [high density liquid; atmospheric pressure and temperatures] 5. Fast fuelling 6. Wide access Utility of IC Engines (includes): 1. High energy and high power 2. Untethered operation 3. Low cost 4. Durability 5. Ability to operate in extreme ambient conditions 6. Challenge: local emissions these are being progressively reduced 7. Fuel versatility 13

14 5. Energy Production Electrical energy can be derived from many sources e.g. nuclear, wind, gas, bio-mass, coal, solar, hydro, etc. Hydrocarbon fuels have many sources including renewable i.e. we are not tied to crude oil [even though oil supplies are large] IC Engines can be run on a wide variety of fuels including renewable Dave Richardson Jaguar Land Rover 2010 Used with kind permission 14

15 1. Global and Local Emissions 2. Energy and Power 3. Comparison - IC Engine/ICE Hybrid vs Pure Battery powertrain 4. Utility of Diesel Fuel and IC Engines 5. Energy Production 6. Conclusions 15

16 6. Conclusions 1. A pure Battery Electric powertrain is currently considered impractical for many types of off-highway machines, and this is expected to remain the same for many years. 2. IC Engine (and/or IC Engine-hybrid) powertrains are expected to remain the best system for most untethered off-highway machines for many years, because: Low cost Fast fuelling High energy Energy access Excellent utility Fuel versatility 3. Emissions are at very low levels and are being further reduced. 16

17 References [1] (accessed 19 August 2017) [2] (accessed 19 August 2017) [3] (accessed 19 August 2017) [4] (accessed 19 August 2017) 17